1. Field of the Invention
The present invention relates to a liquid level sensor, an ampoule, and a liquid amount detection method which are used in a so-called liquid source bubbling system.
2. Related Background Art
There are cases where liquid level sensors are used in so-called liquid source bubbling systems in which a bubbling gas is introduced into an ampoule so as to generate bubbling in a liquid, thereby producing a desirable process gas. Known as an example of the liquid level sensors is one in which a sensor probe is directly immersed in a liquid contained in an ampoule, so as to detect the level of the liquid.
However, from the viewpoint of quality control, the above-mentioned liquid source bubbling systems have been desired to monitor not only whether a liquid exists within the ampoule or not, but also whether the liquid decreases in a normal manner nor not, how much the liquid remains within the ampoule, and so forth.
It is an object of the present invention to provide a liquid level sensor, an ampoule, and a liquid amount detection method which can effectively monitor the state of the liquid.
The inventors conducted diligent studies and, as a result, have found that the number of bubbling periods of the bubbling gas and the bubbling time can be grasped in a liquid source bubbling system since the liquid within the ampoule is stirred during the bubbling of the bubbling gas, thus accomplishing the present invention.
Namely, the present invention provides a liquid level sensor for detecting a level of a liquid contained in an ampoule in which a bubbling gas is introduced, the liquid level sensor comprising a self-heating sensor probe and a temperature measuring sensor probe which are disposed within the ampoule; temperature difference detecting means for detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and bubbling count means for counting the number of bubbling periods of the bubbling gas according to the temperature difference.
When gas bubbles in an ampoule in which a liquid level sensor having a self-heating sensor probe and a temperature measuring sensor probe is disposed, the liquid within the ampoule is stirred, whereby the temperature difference (output potential difference) between the self-heating sensor probe and the temperature measuring sensor probe approaches zero. Therefore, the number of bubbling periods of the bubbling gas can be counted when the number of actions by which the temperature difference between the two sensor probes approaches zero is counted by the bubbling count means. As a consequence, how the liquid within the ampoule is reduced and the like can be grasped. For example, whether the liquid within the ampoule decreases normally or not can be grasped by seeing how many bubbling periods occur during when the liquid within the ampoule changes from a fulfilled state to an empty state.
Preferably, the liquid level sensor further comprises liquid level determining means for determining a level of the liquid according to the temperature difference. Such a liquid level sensor detects the number of bubbling periods of the bubbling gas together with the level of the liquid within the ampoule, thus being able to monitor the state of the liquid within the ampoule more effectively.
Preferably, the bubbling count means has pulse generating means for generating a pulse signal when the temperature difference decreases by a predetermined amount, and a pulse counter for counting the number of pulses generated by the pulse generating means. This can realize the bubbling count means by a simple configuration, and thus is advantageous in terms of cost.
Preferably, the liquid level sensor further comprises display means for displaying the number of bubbling periods counted by the bubbling count means. As a consequence, the operator can immediately grasp the number of bubbling periods by seeing the display means.
Preferably, a plurality of sensor probe sections each comprising the self-heating sensor probe and the temperature measuring sensor probe are provided, while the sensor probe sections have respective front end positions different from each other. As a consequence, how the liquid decreases within the ampoule can be grasped stepwise.
In another aspect, the present invention provides a liquid level sensor for detecting a level of a liquid contained in an ampoule in which a bubbling gas is introduced, the liquid level sensor comprising a self-heating sensor probe and a temperature measuring sensor probe which are disposed within the ampoule; temperature difference detecting means for detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and arithmetic means for determining a bubbling time of the bubbling gas according to the temperature difference and calculating an amount of use of the liquid in the ampoule from the bubbling time.
When gas bubbles in an ampoule in which a liquid level sensor having a self-heating sensor probe and a temperature measuring sensor probe is disposed, the liquid within the ampoule is stirred, whereby the temperature difference (output potential difference) between the self-heating sensor probe and the temperature measuring sensor probe approaches zero. Therefore, by using this characteristic, the arithmetic means calculates the bubbling time of the bubbling gas. Since the amount of use of liquid per unit bubbling time is assumed to be substantially constant, the arithmetic means calculates the amount of use of liquid in the ampoule from the liquid use amount data per unit bubbling time and the bubbling time of the bubbling gas. Since the total amount of liquid within the ampoule in the initial state is determined beforehand, the currently remaining amount of liquid can easily be seen when the amount of use of liquid is known. Since how much the liquid remains within the ampoule can be grasped in an analog fashion as such, it will be sufficient if only one set of self-heating sensor probe and temperature-measuring sensor probe exists, whereby the configuration of the liquid level sensor can be simplified.
Preferably, the liquid level sensor further comprises liquid level determining means for determining a level of the liquid according to the temperature difference. Since such a liquid level sensor detects the amount of the liquid remaining within the ampoule while detecting whether the level of the liquid within the ampoule is higher or lower than a predetermined level, it can monitor the state of the liquid within the ampoule more effectively.
Preferably, the arithmetic means stores liquid use amount data per unit bubbling time beforehand and calculates the amount of use of the liquid in the ampoule from the bubbling time of the bubbling gas and the liquid use amount data per unit bubbling time. In this case, the amount of use of liquid can be obtained without calculating the amount of use of liquid per unit bubbling time in the arithmetic means.
Preferably, the arithmetic means measures an interval from a falling timing period of the temperature difference to a rising timing period of the temperature difference, so as to determine the bubbling time.
Preferably, the liquid level sensor further comprises display means for displaying the amount of use of liquid or remaining amount of liquid in the ampoule calculated by the arithmetic means. As a consequence, the operator can immediately grasp the amount of use or remaining amount of liquid by seeing the display means.
In another aspect, the present invention provides a liquid level sensor for detecting a level of a liquid contained in an ampoule in which a bubbling gas is introduced, the liquid level sensor comprising a self-heating sensor probe and a temperature measuring sensor probe which are disposed within the ampoule; temperature difference detecting means for detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and arithmetic means for counting the number of bubbling periods of the bubbling gas according to the temperature difference and calculating an amount of use of the liquid in the ampoule from the number of bubbling periods.
When gas bubbles in an ampoule in which a liquid level sensor having a self-heating sensor probe and a temperature measuring sensor probe is disposed, the liquid within the ampoule is stirred, whereby the temperature difference (output potential difference) between the self-heating sensor probe and the temperature measuring sensor probe approaches zero. When the amount of use of liquid per unit bubbling time is constant in the bubbling of such a bubbling gas, the bubbling time per bubbling period is assumed to be substantially constant. The present invention determines the amount of use of the liquid in the ampoule by using these bubbling characteristics. Namely, the arithmetic means counts the number of bubbling periods of the bubbling gas, and calculates the amount of use of liquid in the ampoule from the number of bubbling periods and the amount of use of liquid per bubbling period. Since the total amount of the liquid within the ampoule in the initial state is determined beforehand, the currently remaining amount of the liquid can easily be seen if the amount of use of the liquid is known. Since how much the liquid remains within the ampoule can be grasped in an analog fashion as such, it will be sufficient if only one set of self-heating sensor probe and temperature-measuring sensor probe exists, whereby the configuration of the liquid level sensor can be simplified.
Preferably, the liquid level sensor further comprises liquid level determining means for determining a level of the liquid according to the temperature difference. Since such a liquid level sensor detects the amount of the liquid remaining within the ampoule while detecting whether the level of the liquid within the ampoule is higher or lower than a predetermined level, it can monitor the state of the liquid within the ampoule more effectively.
Preferably, the arithmetic means stores liquid use amount data per bubbling period beforehand and calculates the amount of use of the liquid in the ampoule from the number of bubbling periods of the bubbling gas and the liquid use amount data per bubbling period. In this case, the amount of use of liquid can be obtained without calculating the amount of use of liquid per bubbling period in the arithmetic means.
Preferably, the arithmetic means detects at least one of a falling timing of the temperature difference and a rising timing of the temperature difference, and counts the number of bubbling periods of the bubbling gas.
Preferably, the liquid level sensor further comprises display means for displaying the amount of use of liquid or remaining amount of liquid in the ampoule calculated by the arithmetic means. As a consequence, the operator can immediately grasp the amount of use or remaining amount of liquid by seeing the display means.
In another aspect, the present invention provides a liquid level sensor for detecting a level of a liquid contained in an ampoule in which a bubbling gas is introduced, the liquid level sensor comprising a first sensor probe section, disposed within the ampoule, comprising a first self-heating sensor probe and a first temperature measuring sensor probe; a second sensor probe section, disposed within the ampoule so as to have a lower end positioned higher than that of the first sensor probe section, comprising a second self-heating sensor probe and a second temperature measuring sensor probe; temperature difference detecting means for detecting a temperature difference between the first self-heating sensor probe and the first temperature measuring sensor probe, and a temperature difference between the second self-heating sensor probe and the second temperature measuring sensor probe; first arithmetic means for calculating an amount of use of liquid per bubbling period of the bubbling gas according to the temperature difference between the second self-heating sensor probe and the second temperature measuring sensor probe; and second arithmetic means for counting the number of bubbling periods of the bubbling gas according to the temperature difference between the first self-heating sensor probe and the first temperature measuring sensor probe, and calculating an amount of use of liquid in the ampoule from the number of bubbling periods and the amount of use of liquid per bubbling period.
When gas bubbles in an ampoule in which a liquid level sensor having a self-heating sensor probe and a temperature measuring sensor probe is disposed, the liquid within the ampoule is stirred, whereby the temperature difference (output potential difference) between the self-heating sensor probe and the temperature measuring sensor probe approaches zero. When the bubbling time per bubbling period is constant in the bubbling of such a bubbling gas, the amount of use of liquid per bubbling period is assumed to be substantially constant. The present invention determines the amount of use of the liquid in the ampoule by using these bubbling characteristics. Namely, the first arithmetic means initially calculates the amount of use of liquid per bubbling period of the bubbling gas according to an output signal of the second sensor probe section. Then, the second arithmetic means counts the number of bubbling periods of the bubbling gas according to an output signal of the first sensor probe section, and calculates the amount of use of liquid from the number of the bubbling periods and the previously determined amount of use of liquid per bubbling period. Here, since the total amount of liquid within the ampoule in the initial state is determined beforehand, the currently remaining amount of liquid can easily be seen when the amount of use of liquid is known. Since how much the liquid remains within the ampoule can be grasped in an analog fashion as such, it will be sufficient if only one set of first sensor probe section exists.
Preferably, the liquid level sensor further comprises liquid level determining means for determining the level of the liquid according to the temperature difference between the first self-heating sensor probe and the first temperature measuring sensor probe. Since such a liquid level sensor detects the amount of the liquid remaining within the ampoule while detecting whether the level of the liquid within the ampoule is higher or lower than a predetermined level, it can monitor the state of the liquid within the ampoule more effectively.
Preferably, the first arithmetic means counts the number of bubbling periods of the bubbling gas until the level of the liquid reaches a height at which the lower end of the second sensor probe section is located according to the temperature differences between the second self-heating sensor probes and the second temperature measuring sensor probes, and calculates the amount of use of liquid per bubbling period. Since the total amount of liquid within the ampoule in the initial state is determined beforehand in this case, for example, the amount of use of liquid per bubbling period can easily be obtained if the amount of liquid is known at the time when the level of the liquid is located as high as the lower end of the second sensor probe section.
Preferably, in this case, the liquid level sensor has a plurality of second sensor probe sections having respective lower end heights different from each other, whereas the first arithmetic means successively counts numbers of bubbling periods of the bubbling gas until the level of the liquid reaches the respective lower end heights of the second sensor probe sections according to the temperature differences between the second self-heating sensor probes and the second temperature measuring sensor probes, and renews the amount of use of liquid per bubbling period. Consequently, as the liquid within the ampoule decreases, more appropriate amount of use of liquid per bubbling period is obtained.
Preferably, the first arithmetic means detects at least one of a falling timing of the temperature difference between the second self-heating sensor probe and the second temperature measuring sensor probe, and a rising timing of the temperature difference, and counts the number of bubbling periods.
Preferably, the second arithmetic means detects at least one of a falling timing of the temperature difference between the first self-heating sensor probe and the first temperature measuring sensor probe, and a rising timing of the temperature difference, and counts the number of bubbling periods.
Preferably, the liquid level sensor further comprises display means for displaying the amount of use of liquid or remaining amount of liquid in the ampoule calculated by the second arithmetic means. As a consequence, the operator can immediately grasp the amount of use or remaining amount of liquid by seeing the display means.
The present invention provides an ampoule comprising a body for accommodating a liquid; a gas inlet section, provided in the body, for introducing a bubbling gas into the body; a gas outlet section, provided in the body, for leading a gas generated by bubbling of the bubbling gas to the outside of the body; a self-heating sensor probe and a temperature measuring sensor probe which are disposed within the body; temperature difference detecting means for detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and bubbling count means for counting the number of bubbling periods of the bubbling gas according to the temperature difference.
Since the self-heating sensor probe and temperature measuring sensor probe, the temperature difference detecting means, and the bubbling count means are provided as such, how the liquid within the body decreases and so forth can be grasped as mentioned above.
Preferably, the ampoule further comprises a heater for heating the liquid stored within the body, and a temperature sensor for detecting a temperature of the liquid within the body. As a consequence, a process gas having an appropriate temperature can be generated.
Preferably, the gas outlet section is connected to a film-forming apparatus. In this case, the number of processed substrates can be grasped by counting the number of bubbling periods of the bubbling gas in a film-forming process for the substrates.
In another aspect, the present invention provides an ampoule comprising a body for accommodating a liquid; a gas inlet section, provided in the body, for introducing a bubbling gas into the body; a gas outlet section, provided in the body, for leading a gas generated by bubbling of the bubbling gas to the outside of the body; a self-heating sensor probe and a temperature measuring sensor probe which are disposed within the body; temperature difference detecting means for detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and arithmetic means for determining a bubbling time of the bubbling gas according to the temperature difference and calculating an amount of use of liquid from the bubbling time.
Since the self-heating sensor probe and temperature measuring sensor probe, the temperature difference detecting means, and the arithmetic means are provided as such, the amount of liquid remaining within the body can effectively be grasped as mentioned above.
Preferably, the ampoule further comprises a heater for heating the liquid accommodated within the body, and a temperature sensor for detecting a temperature of the liquid within the body. As a consequence, a process gas having an appropriate temperature can be generated.
Preferably, the gas outlet section is connected to a film-forming apparatus. In this case, the number of processed substrates can be grasped by obtaining the total bubbling time of the bubbling gas in a film-forming process for the substrates.
In another aspect, the present invention provides an ampoule comprising a body for accommodating a liquid; a gas inlet section, provided in the body, for introducing a bubbling gas into the body; a gas outlet section, provided in the body, for leading a gas generated by bubbling of the bubbling gas to the outside of the body; a self-heating sensor probe and a temperature measuring sensor probe which are disposed within the body; temperature difference detecting means for detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and arithmetic means for counting the number of bubbling periods of the bubbling gas according to the temperature difference and calculating an amount of use of liquid from the number of bubbling periods.
Since the self-heating sensor probe and temperature measuring sensor probe, the temperature difference detecting means, and the arithmetic means are provided as such, the amount of liquid remaining within the body can effectively be grasped as mentioned above.
Preferably, the ampoule further comprises a heater for heating the liquid accommodated within the body, and a temperature sensor for detecting a temperature of the liquid within the body. As a consequence, a process gas having an appropriate temperature can be generated.
Preferably, the gas outlet section is connected to a film-forming apparatus. In this case, the number of processed substrates can be grasped according to the number of bubbling periods of the bubbling gas in a film-forming process for the substrates.
In another aspect, the present invention provides an ampoule comprising a body for accommodating a liquid; a gas inlet section, provided in the body, for introducing a bubbling gas into the body; a gas outlet section, provided in the body, for leading a gas generated by bubbling of the bubbling gas to the outside of the body; a first sensor probe section, disposed within the body, comprising a first self-heating sensor probe and a first temperature measuring sensor probe; a second sensor probe section, disposed within the body so as to have a lower end positioned higher than that of the first sensor probe section, comprising a second self-heating sensor probe and a second temperature measuring sensor probe; temperature detecting means for detecting a temperature difference between the first self-heating sensor probe and the first temperature measuring sensor probe, and a temperature difference between the second self-heating sensor probe and the second temperature measuring sensor probe; first arithmetic means for calculating an amount of use of liquid per bubbling period of the bubbling gas according to the temperature difference between the second self-heating sensor probe and the second temperature measuring sensor probe; and second arithmetic means for counting the number of bubbling periods of the bubbling gas according to the temperature difference between the first self-heating sensor probe and the first temperature measuring sensor probe and calculating an amount of use of the liquid from the number of bubbling periods and the amount of use of liquid per bubbling period.
Since the first sensor probe section, the second sensor probe section, the temperature difference detecting means, the first arithmetic means, and the second arithmetic means are provided as such, the amount of use and remaining amount of liquid within the body can effectively be grasped as mentioned above. Also, even when the amount of use of liquid per bubbling period fluctuates due to individual differences among apparatus connected to the gas outlet section of the ampoule, appropriate amount of use of liquid and remaining amount of liquid can always be obtained since the first arithmetic means calculates the current amount of use of liquid per bubbling period.
Preferably, the ampoule further comprises a heater for heating the liquid accommodated within the body, and a temperature sensor for detecting a temperature of the liquid within the body. As a consequence, a process gas having an appropriate temperature can be generated.
Preferably, the gas outlet section is connected to a film-forming apparatus. In this case, the number of processed substrates can be grasped according to the number of bubbling periods of the bubbling gas in a film-forming process for the substrates.
The present invention provides a liquid amount detection method comprising the steps of arranging a self-heating sensor probe and a temperature measuring sensor probe within an ampoule into which a bubbling gas is introduced; detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; and counting the number of bubbling periods of the bubbling gas according to the temperature difference. As a consequence, how the liquid decreases within the ampoule and the like can be grasped as mentioned above.
In another aspect, the present invention provides a liquid amount detection method comprising the steps of arranging a self-heating sensor probe and a temperature measuring sensor probe within an ampoule into which a bubbling gas is introduced; detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; determining a bubbling time of the bubbling gas according to the temperature difference; and calculating an amount of use of a liquid accommodated within the ampoule from the bubbling time. As a consequence, the amount of liquid remaining within the ampoule can effectively be grasped as mentioned above.
In another aspect, the present invention provides a liquid amount detection method comprising the steps of arranging a self-heating sensor probe and a temperature measuring sensor probe within an ampoule into which a bubbling gas is introduced; detecting a temperature difference between the self-heating sensor probe and the temperature measuring sensor probe; counting the number of bubbling periods of the bubbling gas according to the temperature difference; and calculating an amount of use of a liquid accommodated within the ampoule according to the number of bubbling periods. As a consequence, the amount of liquid remaining within the ampoule can effectively be grasped as mentioned above.
In another aspect, the present invention provides a liquid amount detection method comprising the steps of using a liquid level sensor constituted by a first sensor probe section, disposed within an ampoule into which a bubbling gas is introduced, comprising a first self-heating sensor probe and a first temperature measuring sensor probe, and a second sensor probe section, disposed within the ampoule so as to have a lower end positioned higher than that of the first sensor probe section, comprising a second self-heating sensor probe and a second temperature measuring sensor probe; detecting a temperature difference between the second self-heating sensor probe and the second temperature measuring sensor probe; calculating an amount of use of liquid per bubbling period of the bubbling gas according to the temperature difference; detecting a temperature difference between the first self-heating sensor probe and the first temperature measuring sensor probe thereafter; counting the number of bubbling periods of the bubbling gas according to the temperature difference; and calculating an amount of use of a liquid accommodated within the ampoule according to the number of bubbling periods and the amount of use of liquid per bubbling period. As a consequence, the amount of liquid remaining within the ampoule can effectively be grasped as mentioned above.